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1. Field of the Invention
The present invention relates to aviation navigation and flight management systems, and more particularly to a navigational flight management system and method for dynamically displaying airports in proximity to the aircraft along with glide range symbology for each airport.
2. Description of the Background Art
Various aviation navigation and flight management systems are known in the art for providing pilots with a wide variety of navigational data. Some navigation systems incorporate features that provide pilots with information about alternate landing destinations. Such systems typically contain a database of airports from which a list of alternate landing locations, such as airports and airstrips, may be selected and displayed. Such systems may also include proximity data such as the distance to each airport, estimated time of arrival, and fuel requirements. The alternate landing location information is typically only used in emergency situations, such as weather avoidance, onboard emergency and/or engine problems, wherein the aircraft would be prevented from landing at the intended destination.
The navigational systems of the background art, however, suffer from a number of significant disadvantages. One primary disadvantage with prior art navigation systems involves the manner in which information pertaining to emergency landing locations is calculated and/or presented to the pilot. For example, in certain geographic areas there may be a relative large number of airports within range of the aircraft. Thus, in an emergency situation the systems of the background art require the pilot to sort through a vast array of numerical data while attempting to find the most suitable alternate landing location depending upon the emergency at hand. As should be apparent, the selection of an alternate landing location and implementation of course correcting maneuvers using such systems requires a significant amount of effort by the pilot.
The task is vastly more complicated in situations wherein engine failure limits the pilot""s options to those locations within gliding range while substantially reducing the time available for the pilot to make and implement flight plan alterations to divert to an alternate emergency landing location. Although aircraft will glide upon experiencing a total loss of engine power, the glide radius is dependent upon the glide ratio characteristics of the particular aircraft and the above ground level (xe2x80x9cAGLxe2x80x9d) altitude. For example, a typical light aircraft is capable of gliding approximately 10 miles for every 1.0 mile of altitude lost. Thus, a typical light aircraft at 15,000 feet (approximately 3 miles) is capable of safely gliding approximately 30 miles to a landing location without engine power, assuming the landing location and terrain are at or near sea level. Thus, the aircraft""s gliding range is a function of the aircraft""s glide ratio and altitude above ground level (xe2x80x9cAGLxe2x80x9d). As should be apparent, however, other factors such as wind conditions can effect an aircraft""s gliding characteristics.
For any given aircraft flying at altitude the predicted maximum glide range for the aircraft may be represented by an imaginary circle, representing the maximum glide distance for the aircraft, transposed over the underlying terrain with the aircraft located at the center. Any landing location within the glide range circle is an available landing location within gliding range in the event of a sudden loss of engine power. As altitude increases, the radius of the glide range circle increases; conversely, as altitude decreases so does the radius of the glide range circle.
When a single engine aircraft experiences engine failure the pilot must quickly ascertain the best emergency landing location within gliding range and make the appropriate control inputs to divert to the emergency landing location. In such situations, requiring the pilot to sift through the vast array of numerical data presented by some prior art flight management systems consumes precious time, diverts the pilot""s attention from other matters during a time of crisis, and is thus not considered an optimal means of conveying the information in such situations. The background art further reveals flight management systems that display the glide range of the aircraft by generating and electronically displaying a circle around the aircraft as discussed hereinabove. If an airport, or other suitable landing location, is within the circle, then it is within gliding distance. While such a graphical representation of glide range is generally sufficient for present awareness and indication, it is of little assistance in providing the pilot with the availability of future potential target landing areas, and does not assist the pilot in selecting and plotting a course wherein emergency landing options are maximized for the duration of the flight. In addition, such systems fail to take into account differing elevations of the respective airports. The flight management systems known in the art simply fail to provide a system that provides a pilot with real time altitude dependent gliding ranges to various alternate potential landing locations.
Accordingly, there exists a need for an improved flight management system capable of providing a pilot with an improved graphical representation of alternate landing locations within gliding distance.
There also exists a need for a flight management system that simultaneously provides the pilot with glide ranges to alternate landing locations for use in evaluating future course options.
The present invention provides a flight management system and method capable of providing the pilot with a real time display of various landing locations within gliding range in a format that assists the pilot in evaluating both present and future course options thereby maximizing safety. The present invention provides an improvement to known flight management systems by simultaneously displaying gliding range information for a number of alternate landing locations thereby providing the pilot with current and future emergency landing options in the event of sudden engine failure.
The present invention presents information to the pilot by complementing the flight management system""s conventional moving map display with airports and other landing locations enhanced to include circular symbols centered on each landing location. Each circular symbol represents a sectional view of an imaginary inverted cone, having the apex thereof centered on its respective airport. The size and shape of the cone is based on the gliding performance of the aircraft and the altitude differential between the aircraft and that particular landing location. As the altitude differential increases the radius of the circle increases. Conversely as the altitude differential decreases, the radius of the circle decreases. Each three dimensional inverted cone is represented as a circle having the airport at the center for each airport displayed. As long as the aircraft is anywhere within any one of the three-dimensional inverted cones displayed, as represented by one or more circles on a two dimensional display, it can safely glide to the landing location. This display concept is selectively referred to herein as xe2x80x9ccones of safety.xe2x80x9d The present invention thus provides a flight management system that generates and displays cones of safety for each landing location, e.g. airport and/or landing strip, appearing on the flight management display. By displaying glide range information in this manner the pilot is better able to plot a course that maximizes time within cones of safety. The invention is suitable for incorporation with various existing flight management systems, and cones of safety may be displayed in an overlaid manner along with other useful navigational information.
The present invention maintains real time representations of cones of safety for each landing location displayed on a GPS/GIS enabled dynamic navigational map generated by the flight management system. Thus, unlike glide range displays that are centered on the aircraft as disclosed in the background art, the present invention generates circular glide range displays that are centered on each potential landing area. If the aircraft is operating in an area of overlapping glide range circles, then multiple options are available for an emergency landing as the aircraft is within gliding range of each airport associated with the overlapping cones of safety. In addition, a significant improvement is realized in that by simultaneously displaying cone of safety information for each potential landing location, the pilot is able to chart a course that maximizes emergency landing options. By referencing the various cones of safety displayed, the pilot is able to execute a flight plan having a course that maximizes the flight time within cones of safety thus maximizing emergency landing options while minimizing flight time void of emergency landing options. Thus, the pilot is provided with advance warning if the projected course does not intersect cones of safety and is thus void of emergency landing airports. As should be apparent, providing such useful information in advance allows the pilot to maximize safety by altering course so as to maximize flight time within one or more cones of safety.
Accordingly, it is an object of the present invention to provide an improved flight management system.
Still another object of the present invention is to provide a flight management system capable of displaying glide range symbology relative to potential emergency landing locations.
Yet another object of the present invention is to provide a flight management system adapted to calculate and display glide range information, based on altitude and aircraft glide ratio, for a plurality of landing locations.
Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.